Safety blow off device



H. HENDERSON SAFETY BLOW-OFF DEVICE Filed Aug. 31 1925 gwue'nliol Patented May 24, 1932 UNITED STATES PATENT OFFICE HERBERT HENDERSON, OF PORT ARTHUR, TEXAS, ASSIGNOR TO GULF REFINING GOM- PANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF TEXAS SAFETY 31.0w one nnvrcn Application filed August 31, 1925. Serial No. 53,583.

This invention relates to safety blow-off devices for pressure stills and it comprises an encased safety valve located on the still or on a pressure line leading to or from the still, a pipe leading from the casing of the valve to an expansion receptacle, advantageously, means for cooling blow-off gases after they have passed the valve and prior to the 'timeof reaching the receptacle and also, advantageously, means for cooling the gases after they leave the receptacle; and more specifically, the invention comprises the combination of such an arrangement as described with means for pumping out the receptacle, with fire extinguishing means for the receptacle com prising either a live steam or a foam connection, and with a steam connection on the pressure line at a point near the safety valve, for the purpose of admitting steam near the safet valve to extinguish any fire and blow the hue clean after it has been used; all as more fully hereinafter set forth and as claimed.

In the production of lower boiling hydrocarbons from higher boiling hydrocarbons by pressure distillation, very high temperatures and pressures are used, the temperature ranging from 600 to 1200 F. and higher and pressures running anywhere from atmos phere up to thousands of pounds. Different types of pressure stills are used. Sometimes the still consists of coiled pipes located in the furnace and sometimes the still is of a boiler type, that is, is a simple shell, or is of the wa In additionto the in the pipe coil type of still, the safety valve is located on the outlet line. In the boiler type of still the safety valve is usually located directly on the still or on the vapor line leading from the still to the first condenser. It is advantageous to locate the safety valve as near to the still as possible. When the safety valve blows due to the pressure in the still exceeding the pressure to which the valve is set, there is an escape of inflammable gases and vapors, and since the valve is located near the still and since the still is in proximity to the fire which is heating it, there is danger that the escaping gases and vapors from the safety valve will become ignited. This not only may be disastrous since in an oil refinery there is always great danger that a fire once started will spread, but in addition there is the loss of vapors of valuable oils.

In accordance with my invention, I locate the safety valve at the most desirable point, and this may be very near the still. The safety valve is surrounded by a casing and from the casing a pipe leads to an expansion tank so that when the safety valve blows, the gases and vapors do not escape to the atmosphere at a point near the still but are conducted from the casing surrounding the safety valve by means of the pipe to the exwater condenser in the line'leading from the safety valve to the expansion tank. In addition when the exigencies of a particular case demands, I pass the gases from the expan sion tank through a condenser and in this way save all of the vapors of hydrocarbons which are condensable. This not only lessens the likelihood of fire when the uncondensable gases are vented to the atmosphere, but insures venting the gases at a very low temperature. I provide arrangements whereby the condenser may or may not be used.

In the accompanying drawings showing one form of a specific embodiment of my invention,

Fig. 1 is a top plan diagrammatic view of a series of stills in communication with a blow-off tank;

Fig. 2 is a side elevation of the expansion tank with a barometric condenser shown partlyin section;

Fig. 3 is a diagrammatic view illustrating the valve applied to a heating element of a pipe still and Fig. .l is a view partly in section of one form of safety valve with enclosing casing which may be used.

Fig. 5 is a side elevation of a shell still and the herein claimed safety blow-off device.

Referring to the drawings (A) represents a battery of pressure stills, of any number and of any type, (the boiler type still or the pipe type pressure still). In Fig. 3, 1 indicates a fire box and the super-structure of a pipe still, all forming no part of the present invention. Reference numeral 2 indicates the heating element in the still and 3 the inlet or outlet to the heating element or heating coil. The safety valve indicated generally by numeral 4 may be used upon the inlet as well as upon the outlet of the coil or upon both. The safety valve may be of any usual type which can be set to blow at a predetermined pressure but it is provided with a casing 5 (see Fig. 4) which completely surrounds the valve including the stem and the setting and adjusting mechanism so no leakage can occur, and to the casing is connected the line 6 leading past condenser 7, Fig. 1, having water inlet 8 and outlet 9 and terminating in manifold or expansion drum 10. The ex pansion drum is in direct communication with blow-ofi tank 11 and this tank is provided with a high stack 12 and weighted valve or damper 13. In communication with the stack 12 through line 14 is the barometric condenser 15 having water inlet 16 and leg 17 tog-ether with a syphon control 18 for maintaining the level of the water at the desired point in the known way. Water s drawn through the syphon 18 while oil above the level of the water is withdrawn through line 19 to the blow-oif tank from whence it canbe pumped out for use.

The condensers 7 Fig. 1 may be surface condensers or water cooled condensers of any design and the condenser attached to the blow-off tank may be of any design; those illustrated are very well adapted for the purpose. When the still blows off a portion of the vapors accompanying the gases will con dense in the line between the still and the blow-off tank and the balance of the gas will go through the vapor line 14 into the barometric condenser head, condensed oils from the vapor running back into the tank and water from the condenser overflowing to the sewer. If it is desired to vent the gases directly to the atmosphere at a point far from the still which may be done when they are relatively cool, the valve 20 in the vapor line to the barometric condenser head may be closed.

Each line is provided with a steam connection at a point preferably near the safety valve as illustrated by reference numeral 21.

This is for the purpose of admitting steam near the safety valve to extinguish any fire and to blow the line clean after it has been used. Each such line is provided with a check valve 22 to prevent hot oil from backinginto the steam line. The damper on top of the stack 12 of the blow-0E tank may be weighted to open to the atmosphere when the still pressure is relieved through the safety valve into the blow-off tank and to immediately close when the blowing ceases. This will prevent fire in the blow-off tank. The blow-off tank is further provided with the inlet line 23 to be used as a live steam connection for fire extinguishing purposes. And line 24 leads from the usual foam box for use in case the hot oil in the tank should become ignited. 25 indicates the pumping out line connected at the bottom of the tank for pumping back to the charging stock the oil which is blown from the heating element, and 26 illustrates a fire wall around the blowoff tank.

Referring to Fig. 5, an ordinary shell type still is indicated by A, this being the still to which my invention is accessory. The vapors leave the still through line 3 which carries them to a condenser where they are recovered as a liquid. A conventional pressure reducing valve 27 is shown interposed in line 3. This reducing valve 27 is the reducing valve which is invariably present on the vapor outlet of every high pressure still and essential to the maintenance of a higher pressure therein than exists in the container to which the condenser discharges. In open communication with the vapor line 3 is a safety valve 4 set to open at a predetermined pressure in excess of that pressure which it is desired to maintain by valve 27. In common with all safety valves the valve 4; functions by relieving the system of a portion of the generated vapors sufficient to reduce the pressure in still A to a pressure not substantially above that which it is intended to maintain by pressure reducing valve 27. 1V hatever vapors may chance to be vented by the safety valve 4; are conducted byline 6 and expansion drum 10 to blow-off tank 11. The

condenser 7, having water inlet 8 and water outlet 9 is interposed in the line 6 to condense as much of the escaping vapor as possible or to cool it below ignition temperature. A steam line 21 is connected with line 6 just beyond the safety valve 4 to permit the introduction of steam at this point. All other elements of Fig. 5 are identical with Fig. 2 and the description of that figure is directly applicable thereto.

As stated the safety valve and the blowofi tank may be used in connection with pipe pressure stills or the ordinary boiler pressure stills and the valves may be placed on the inlet line or outlet line. Fig. 1 illustrates a battery of twelve stills each having the outlet line equipped with the valve leading to the blow-off tank 11. At times it may be desirable not to use the condensers 7, but ordinarily I find that it is better to condense as much as possible of vapors which are blown from the still. The gases are cooled below their condensation point while out of contact with the atmosphere and fire entirely prevented. Incidentally there is the important advantage that there is no loss of oil since with the use of one or more condensers, the vapors are not allowed to escape to the atmosphere.

What I claim is 1. The combination with a pressure still operable at a predetermined pressure, of a valve in free communication therewith and arranged to automatically open when sub jected to a definite pressure greater than said predetermined pressure and to automatically close when less than said predetermined pressure prevails, cooling means for vapors and gases passing said valve when opened, a blowofi tank, a conduit leading from said cooling means to said blowoif tank, and a closure piece on the blowoif tank to permit the escape of gases therefrom while substantially preventing the entrance of air thereto.

2. The combination with a pressure still operable at a predetermined pressure, of a safety relief valve in free communication therewith and arranged to automatically open when subjected to a definite pressure greater than said predetermined pressure and to automatically close when less than said predetermined pressure prevails, a blowoff tank, a conduit leading from said valve to said blowofi tank, means for introducing a fire extinguishing agent into the system, beyond said automatically opening valve and a closure piece on the blowofl" tank to permit the escape of gases therefrom while substantially preventing the entrance of air thereto.

3. The combination with a pressure still operable at a predetermined pressure, of a safety relief valve in free communication therewith and arranged to remain closed at said predetermined pressure, and arranged to automatically open when subjected to a definite excess pressure, and arranged to close upon the cessation of said excess pressure; a blowoff tank; a conduit leading from said valve to said blowofii tank; means for introducing a fire extinguishing agent into the system, beyond said automatically opening valve and a closure piece on the blowoff tank to permit the escape of gases therefrom while substantially preventing the entrance of air thereto. 7

4;. The combination with a pressure still operable at a predetermined pressure, of a valve in free communication therewith and arranged to remain closed at said predetermined pressure, and arranged to automatically open when subjected to a definite excess pressure, and arranged to close upon the cessation of said excess pressure; a blowoff tank; a conduit leading from said valve to said blowoif tank; and a closure piece on the blowolf tank to permit the escape of gases therefrom while substantially preventing the entrance of air thereto.

In testimony whereof, I have hereunto affixed my signature.

HERBERT HENDERSON. 

